PHTSEMA. 21 



solida, Brug. - tortuosa, A. Adams. 



speciosa, A. Adams. truncatula, Brug. 



succisa, Ehrerib. 



Sub-gen. dinia, H. and A. Adams. 



Shell ovoid, posteriorly sub-truncated, longitudinally striated ; 

 inner lip strongly truncated, and ending anteriorly in a den- 

 tiform plate. 



dentifera, A. Adams. nonscripta, A. Adams. 



monodonta, A. Adams. 



Sub-gen. sao, H. and A. Adams. 



Shell pyriform, gibbose anteriorly, umbilicated; apex truncate, 

 impressed, not perforate ; aperture contracted posteriorly, greatly 

 dilated in front ; columella reflexed, not truncate ; outer lip pro- 

 duced and angulated behind. 



pyriformis, A. Adams. 



Genus PHYSEMA, H. and A. Adams. 



Shell small, hyaline, globose, umbilicated, fragile, 

 longitudinally finely striated ; spire none ; aperture nar- 

 row posteriorly, greatly dilated anteriorly ; columella 

 somewhat arcuated, reflected ; outer lip acute, free pos- 

 teriorly, dilated in the middle. 



Ex. P. hiemalis, Coiithouy, pi. 57, fig. 6. 



This genus is founded on a small, but very peculiarly 

 formed shell, having somewhat the appearance of Akera or 

 Lophocercus, but which appears to be sufficiently different 

 from either. It has been procured chiefly, hitherto, from 

 the stomachs of codfish in Massachusetts Bay, and the 

 animal has not been observed. 



VOL. II. E 



